Winchell Limestone
(= Chico Ridge Ls.)


Fusulinidae of the Winchell Formation, Texas

" The Winchell Formation is the thickest and best exposed limestone unit in the Canyon Group and separates the Wolf Mountain Shale from the Placid Shale in the Canyon type area. The Canyon type area is included in the southernmost portion of the index map of Palo Pinto, Stephens and Wise counties. Northeastward of the Brazos River the Winchell Limestone grades laterally into shale and sandstone, leaving the overlying Placid Shale resting directly on the underlying Wolf Mountain Shale.

" It was first mapped as the Graford limestones by Plummer (1919), and subsequently called Adams Branch by Plummer & Moore (1921), because of its apparent equivalency with the Colorado River Adams Branch. The unit was later named Merriman by Plummer & Hornberger (1935). It was correlated into the Brazos River valley by Cheney (1910), and by Feray & Jenkins (1954). Its formational status was formally given by Eargle (1960), a use followed by Laury (1962).  "

" Chico Ridge Bioclastic Bank.-- Northeast of the Jack County clastic facies, on the western and eastern shores of Lake Bridgeport in Wise County, is a limestone body informally referred to as the Chico Ridge Bioclastic Bank but formally called the "Winchell Limestone". A maximum thickness of 300 feet has been reported in Wise and Montague counties (Scott & Armstrong, 1932).  "



Geology pictures:

Winchell Limestone:
Lake Brownwood spillway
Lake Brownwood spillway
Jack co., Tx.
Palo Pinto co., Tx.
Palo Pinto co., Tx.
Palo Pinto co., Tx.
Palo Pinto co., Tx.
Palo Pinto co., Tx.
 
Chico Ridge Limestone:
Wise co., Tx.
Wise co., Tx.
Wise co., Tx.
Rock Hill Limestone:  This layer is exposed on the northeast side of the lake but at a higher elevation.
Wise co., Tx.
Wise co., Tx.
 

Fossil pictures:

Crinoid columnals from Winchell Ls.

Jack co., Tx.